n. Encouragement.n. The interior portion of a mass of masonry, as the portion between the up-stream and down-stream faces of a masonry dam. Commonly called the backing.n. The impervious vertical wall of masonry, concrete, or even clay puddle which is placed inside an earth embankment which forms a dam or a reservoir bank, for the purpose of preventing leakage through the embankment. Commonly called core-wall if of masonry or concrete, and puddle-wall if of clay.